Complex permittivity, permeability, and X-band microwave absorption of CaCoTi ferrite composites

Abstract

The effect of Co2+Ti4+ substitution on complex permeability, permittivity, and microwave absorption has been studied for [Ca(CoTi)xFe12−2xO19]96.0[La2O3]4.0 ferrite-epoxy composites, wherein x varies from 0 to 1.0 in steps of 0.2, in the frequency range from 8.0 to 12.4 GHz. The ferrites with x>0 exhibit significant dispersion in complex permittivity (ε′−jε″) with the maximum value of ε″ observed for x equal to 0.2. The dispersion in complex permeability (μ′−jμ″) is not significant. The variations of reflection loss and percentage absorption have been studied as a function of frequency, Co2+Ti4+ content, and thickness of the absorber. A maximum reflection loss of 31.0 dB is obtained for composites with x equal to 0.2 and absorber thickness of 2.5 mm. The experimental values of the matching frequency and the matching thickness agree well with the theoretical values obtained from an impedance-matching solution map.